4 files changed, 52 insertions, 15 deletions

diff --git a/lib/CodeGen/CGObjCMac.cpp b/lib/CodeGen/CGObjCMac.cpp
index e000bd22aa..098a0f8221 100644
--- a/lib/CodeGen/CGObjCMac.cpp
+++ b/lib/CodeGen/CGObjCMac.cpp
@@ -4275,13 +4275,19 @@ void CGObjCNonFragileABIMac::FinishNonFragileABIModule() {
 /// message dispatch call for all the rest.
 ///
 bool CGObjCNonFragileABIMac::LegacyDispatchedSelector(Selector Sel) {
-  if (CGM.getCodeGenOpts().ObjCLegacyDispatch)
+  switch (CGM.getCodeGenOpts().getObjCDispatchMethod()) {
+  default:
+    assert(0 && "Invalid dispatch method!");
+  case CodeGenOptions::Legacy:
     return true;
-  /* Leopard */
-  if (CGM.getContext().Target.getTriple().getOS() == llvm::Triple::Darwin &&
-      CGM.getContext().Target.getTriple().getDarwinMajorNumber() <= 9)
+  case CodeGenOptions::NonLegacy:
     return false;
-  
+  case CodeGenOptions::Mixed:
+    break;
+  }
+
+  // If so, see whether this selector is in the white-list of things which must
+  // use the new dispatch convention. We lazily build a dense set for this.
   if (NonLegacyDispatchMethods.empty()) {
     NonLegacyDispatchMethods.insert(GetNullarySelector("alloc"));
     NonLegacyDispatchMethods.insert(GetNullarySelector("class"));
@@ -4311,6 +4317,7 @@ bool CGObjCNonFragileABIMac::LegacyDispatchedSelector(Selector Sel) {
     NonLegacyDispatchMethods.insert(
       CGM.getContext().Selectors.getSelector(3, KeyIdents));
   }
+
   return (NonLegacyDispatchMethods.count(Sel) == 0);
 }
 
diff --git a/lib/Driver/ToolChains.h b/lib/Driver/ToolChains.h
index 9e61b8972f..a307b2bdac 100644
--- a/lib/Driver/ToolChains.h
+++ b/lib/Driver/ToolChains.h
@@ -168,6 +168,12 @@ public:
     return (getTriple().getArch() == llvm::Triple::arm ||
             getTriple().getArch() == llvm::Triple::thumb);
   }
+  virtual bool UseObjCMixedDispatch() const {
+    // Mixed dispatch is only used on x86_64 for 10.6 and later.
+    return (!isTargetIPhoneOS() &&
+            getTriple().getArch() == llvm::Triple::x86_64 &&
+            !isMacosxVersionLT(10, 6));
+  }
   virtual bool IsUnwindTablesDefault() const;
   virtual unsigned GetDefaultStackProtectorLevel() const {
     // Stack protectors default to on for 10.6 and beyond.
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 2e8db0062d..8ad04aa508 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -1230,13 +1230,17 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     if (Args.hasArg(options::OPT_fobjc_nonfragile_abi) ||
         getToolChain().IsObjCNonFragileABIDefault()) {
       CmdArgs.push_back("-fobjc-nonfragile-abi");
-      
-      // -fobjc-legacy-dispatch is only relevant with the nonfragile-abi, and
-      // defaults to off.
-      if (Args.hasFlag(options::OPT_fobjc_legacy_dispatch,
-                       options::OPT_fno_objc_legacy_dispatch,
-                       getToolChain().IsObjCLegacyDispatchDefault()))
-        CmdArgs.push_back("-fobjc-legacy-dispatch");
+
+      // -fobjc-dispatch-method is only relevant with the nonfragile-abi, and
+      // legacy is the default.
+      if (!Args.hasFlag(options::OPT_fobjc_legacy_dispatch,
+                        options::OPT_fno_objc_legacy_dispatch,
+                        getToolChain().IsObjCLegacyDispatchDefault())) {
+        if (getToolChain().UseObjCMixedDispatch())
+          CmdArgs.push_back("-fobjc-dispatch-method=mixed");
+        else
+          CmdArgs.push_back("-fobjc-dispatch-method=non-legacy");
+      }
     }
   }
 
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index db937bc4c7..68842a4015 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -178,8 +178,16 @@ static void CodeGenOptsToArgs(const CodeGenOptions &Opts,
   }
   if (Opts.NoZeroInitializedInBSS)
     Res.push_back("-mno-zero-initialized-bss");
-  if (Opts.ObjCLegacyDispatch)
-    Res.push_back("-fobjc-legacy-dispatch");
+  switch (Opts.getObjCDispatchMethod()) {
+  case CodeGenOptions::Legacy:
+    break;
+  case CodeGenOptions::Mixed:
+    Res.push_back("-fobjc-dispatch-method=mixed");
+    break;
+  case CodeGenOptions::NonLegacy:
+    Res.push_back("-fobjc-dispatch-method=non-legacy");
+    break;
+  }
   if (Opts.SoftFloat)
     Res.push_back("-msoft-float");
   if (Opts.UnwindTables)
@@ -820,7 +828,6 @@ static void ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args,
   Opts.FloatABI = getLastArgValue(Args, OPT_mfloat_abi);
   Opts.LimitFloatPrecision = getLastArgValue(Args, OPT_mlimit_float_precision);
   Opts.NoZeroInitializedInBSS = Args.hasArg(OPT_mno_zero_initialized_in_bss);
-  Opts.ObjCLegacyDispatch = Args.hasArg(OPT_fobjc_legacy_dispatch);
   Opts.SoftFloat = Args.hasArg(OPT_msoft_float);
   Opts.UnwindTables = Args.hasArg(OPT_munwind_tables);
   Opts.RelocationModel = getLastArgValue(Args, OPT_mrelocation_model, "pic");
@@ -830,6 +837,19 @@ static void ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args,
 
   Opts.MainFileName = getLastArgValue(Args, OPT_main_file_name);
   Opts.VerifyModule = !Args.hasArg(OPT_disable_llvm_verifier);
+
+  if (Arg *A = Args.getLastArg(OPT_fobjc_dispatch_method_EQ)) {
+    llvm::StringRef Name = A->getValue(Args);
+    unsigned Method = llvm::StringSwitch<unsigned>(Name)
+      .Case("legacy", CodeGenOptions::Legacy)
+      .Case("non-legacy", CodeGenOptions::NonLegacy)
+      .Case("mixed", CodeGenOptions::Mixed)
+      .Default(~0U);
+    if (Method == ~0U)
+      Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args) << Name;
+    else
+      Opts.ObjCDispatchMethod = Method;
+  }
 }
 
 static void ParseDependencyOutputArgs(DependencyOutputOptions &Opts,